Background Information to the
Boston Central Artery/Tunnel Settlement with the
Commonwealth of Massachusetts and the
U.S. Attorney for Massachusetts
January 23, 2008


Bechtel Infrastructure Corporation and Parsons Brinckerhoff (B/PB) have reached an agreement that settles claims by the Commonwealth of Massachusetts and the U.S. Attorney for the District of Massachusetts regarding our work as management consultant for the Boston Central Artery/Tunnel project, also known as the Big Dig.

The settled claims relate to the July 2006 collapse of tunnel ceiling panels in the I-90 connector tunnel that resulted in the tragic death of Milena Del Valle, B/PB's management of slurry wall construction and a slurry wall breach on a panel in the C17A1 mainline tunnel, oversight of time and materials billing, and delivery of "out-of-spec" concrete to the project.

This paper is not an exhaustive summary of issues addressed in the agreement; it is intended to supplement settlement documents, providing context and additional background information.


Project Overview

  • Roles and Responsibilities

Settlement Issues

  •     I-90 Connector Tunnel Ceiling Panels
  •     Slurry Wall Construction 
  •     Slurry Wall Breach
  •     Oversight of Time and Materials Billing
  •     Concrete Program
  •     Programmatic Upgrades

Additional Information

  •     Cost Growth
  •     Integrated Project Organization
  •     Tunnel Leaks


The Central Artery/Tunnel is the largest and most complex urban transportation project ever undertaken in the United States. It consists of 161 lane miles of highway in a 7.5-mile corridor, about half in tunnels, and includes four major highway interchanges and two major bridges— all built over and under a functioning city with remarkably little disruption.

The Central Artery/Tunnel has won leading design, engineering and other awards from the Federal Highway Administration (FHWA), American Society of Civil Engineers, American Association of State Highway and Transportation Offices, American Institute of Architects, American Road & Transportation Builders Association, and many other distinguished professional and civic groups.

Roles and Responsibilities

Over two decades of design and construction, the project spanned seven state and four federal administrations. No fewer than 20 state and federal agencies managed, directed, or audited the project.

To build the Central Artery/Tunnel, the Massachusetts Highway Department (MHD) and later Massachusetts Turnpike Authority (MTA) contracted with 38 different section design consultants and had approximately 142 construction contracts. MHD/MTA selected and awarded all of the design and construction contracts. From 1985 through 2005, B/PB served as the management consultant to both MHD and MTA.

Section design consultants prepared, stamped, and were responsible for the final designs. Construction contractors were responsible for building the facilities and meeting all of the requirements of their respective contracts with MHD/MTA. B/PB was responsible for monitoring the contractors' compliance with terms and conditions of their respective construction contracts.

In 1999, just as construction activity was peaking, the MTA converted from a traditional program management model to an integrated project organization, which led to the management shifting to MTA. Although adopted for the stated purpose of streamlining the management structure and trimming costs, it also had the effect of blurring accountability and responsibilities, and discouraging proactive project management. 

Describing the functional effect of the IPO, a National Academy of Engineers report stated: “…during the transition to the IPO structure in 1997-1999, the best-qualified person available for a particular managerial position was selected regardless of organizational affiliation (the position of project director, who reports to the chairman of the MTA, was reserved for an MTA employee). In effect, B/PB is no longer in the role of a project Management Consultant but supplies highly qualified people to augment the staff of the MTA.” (See more information on the IPO below.)


I-90 Connector Tunnel Ceiling Panels

The ceiling panels that fell in July 2006 were located in a portion of the I-90 eastbound tunnel under D St. in South Boston that connects to the Ted Williams tunnel. In order to ventilate the tunnel, a suspended ceiling was specified to create an exhaust duct between the ceiling and tunnel roof.

This portion of the tunnel was constructed before the rest of the connector tunnel in order to support the opening of the Ted Williams tunnel. As such, the design of the tunnel consists of cast-in-place concrete heavily reinforced with rebar and without any channel inserts or girders embedded in the tunnel roof. The tunnel ceiling is hung from brackets attached to the roof slab with epoxy anchor bolts.

The final design called for concrete ceiling panels to be bolted into steel frames, which in turn were supported by adjustable hanger rods connected to roof brackets. The brackets were to be anchored to the concrete roof with stainless steel bolts held in place by epoxy adhesive. Epoxy adhesive anchors had been used previously by MHD to retrofit ceilings in the nearby Sumner and Callahan tunnels, and to support the ceiling in the Ted Williams tunnel.

In findings released July 10, 2007, the National Transportation Safety Board (NTSB) found that the probable cause of the ceiling-panel collapse was the inappropriate use of Powers Fasteners’ Power-Fast Fast Set epoxy anchor adhesive, which had poor creep resistance: that is, an epoxy formulation that was not capable of sustaining long-term loads. Over time, the epoxy deformed and fractured until several ceiling support anchors pulled free and allowed a portion of the ceiling to collapse.

The NTSB found that the use of the inappropriate epoxy formulation resulted from the following:

  • The failure of Gannett Fleming, Inc., and B/PB to identify potential creep in the anchor adhesive as a critical long-term failure mode and to account for possible anchor creep in the design, specifications, and approval process for the epoxy anchors used in the tunnel.
  • A general lack of understanding and knowledge in the construction community about creep in adhesive anchoring systems.
  • The failure of the epoxy vendor, Powers Fasteners, Inc., to provide the Central Artery/Tunnel project with sufficiently complete, accurate, and detailed information about the suitability of the company’s Fast Set epoxy for sustaining long-term tensile loads.

The NTSB also found the following contributing factors to the ceiling-panel collapse:

  • The failure of Powers Fasteners to determine that the anchor displacement that was found in the high occupancy vehicle tunnel in 1999 was a result of anchor creep due to the use of the company’s Power-Fast Fast Set epoxy, which was known by the company to have poor long-term load characteristics.
  • The failure of Modern Continental Construction Company and B/PB, subsequent to the 1999 anchor displacement, to continue to monitor anchor performance in light of the uncertainty as to the cause of the failures.
  • The Massachusetts Turnpike Authority's failure to implement a timely tunnel inspection program that would likely have revealed the ongoing anchor creep in time to correct the deficiencies before an accident occurred.

The NTSB identified the following safety issues during its investigation:

  • Insufficient understanding among designers and builders of the nature of adhesive anchoring systems.
  • Lack of standards for the testing of adhesive anchors in sustained tensile-load applications.
  • Inadequate regulatory requirements for tunnel inspections.
  • Lack of national standards for the design of tunnel finishes.

Bruce A. Magladry, director of the National Transportation Safety Board’s Office of Highway Safety, said of his investigation of the ceiling collapse, “There's no malice we find in the efforts of any of the people involved in this construction project. These are conscientious people, trying to do a job.”

On August 8, 2007, a Suffolk County. Massachusetts, grand jury returned an indictment against Powers Fasteners. The Commonwealth alleges that Powers Fasteners knew that its epoxy product was being used in the tunnel, and when provided with the opportunity, failed to differentiate to project managers between its Fast Set and Standard Set products. The Commonwealth further alleges that Powers Fasteners failed to reveal this fact in either its marketing material or when it was specifically asked, and had the necessary knowledge and the opportunity to prevent the fatal ceiling-panel collapse but failed to do so.

Slurry Wall Construction

Most of the tunnel walls on the I-93 mainline tunnel contracts were slurry walls. Slurry is a viscous liquid ordinarily containing bentonite clay which holds excavations open prior to concrete placement.

Slurry wall construction is a time-sensitive operation. The overall objective is to complete the construction of the concrete panel as expeditiously as practicable. Once an excavation is started, the panel should be completed without interruption; this is especially important in an urban environment where abutting properties and utilities are at risk to any ground movements that could result from a slurry trench excavation collapse.

Contract specifications stated that concrete placement could not occur on a slurry wall construction unless the slurry itself was within certain specified tolerances. The tolerances were specified by the designers of the tunnel and differed among various construction contracts on the project; however, all of the specifications were within generally accepted constructions standards.

B/PB field personnel were required to assure that concrete placement cards were properly completed by the construction contractors and a representative from B/PB. Concrete placement cards were required for every concrete placement on the Central Artery/Tunnel project. The purpose of the concrete placement card was to document that all inspections had been completed by the construction contractors’ inspectors as well as B/PB’s field engineers prior to the placement of concrete. Project procedures stated that the construction contractor was not authorized to place concrete if either the construction contractors or B/PB failed to complete the concrete placement card properly.

Approximately 230 concrete slurry wall panels were constructed on C17A1 between 1998 and 2001. Concrete placement cards for approximately 210 of these panels were not properly completed by B/PB and the construction contractor as required, and in a number of cases, the slurry was "out-of-spec."

Slurry was not incorporated into the final constructed product. In most instances, the deviations from the specified tolerances were slight, and in many cases the "out-of-spec" slurry on C17A1 would have met the slurry tolerances for other sections of the Central Artery/Tunnel.

Slurry Wall Breach

In September 2004, a breach occurred in the I-93 northbound tunnel wall, in one of the deepest areas of the tunnel alignment. Water and sand flowed into the tunnel, requiring the closure of one lane during peak afternoon traffic before the wall was patched that evening. The breach was the result of a series of construction failures completely independent of the characteristics of the slurry being used during that construction.

This wall breach resulted from a series of construction contractor errors, compounded by inadequate oversight. B/PB missed an opportunity to direct the contractor to correct the specific wall problem ahead of time. B/PB publicly acknowledged its responsibility at the time and paid its share of the cost of permanently fixing this portion of the wall.

The breach was caused by improper construction of a single wall bay. The construction contractor failed to follow its own approved procedures, which called for removing an end stop and clearing away dirt and debris trapped by overflow concrete in its section of the wall. This pocket of material (clay inclusion) eventually allowed water—under high pressure at depth—to find a path through the wall and into the tunnel.

A B/PB field engineer observed and noted the construction defect in 1999, and should not have allowed construction to proceed. In 2001, after the contractor identified a leak at the same wall location, B/PB's resident engineer called on the contractor to undertake nondestructive testing to assure that the wall panel met contract specifications, and to submit a procedure for repair; however, B/PB did not follow up to make certain this was done.

Although responsibility lies with the contractor to ensure proper construction of the wall, B/PB should have directed the contractor to correct the problem during the initial construction. Later, B/PB should have made certain the contractor carried out necessary tests and repairs properly.

To minimize the possibility that similar issues might arise elsewhere, between October 2004 and March 2005, project teams conducted physical inspections of approximately 1,600 tunnel wall panels. Of these, only one (in addition to the panel breached in September 2004) required major repair. These inspections and repairs were carried out at the expense of the contractor and B/PB.

Oversight of Time and Materials Billing

Generally, construction contracts on the Central Artery/Tunnel were fixed price contracts. Frequently, such contracts were modified to account for unanticipated additional work. Much of this additional work was paid on a time-and-material basis. This meant that the general contractor and its subcontractors (contractors) were paid by for actual expenses plus 10 percent for overhead and an additional 10 percent for profit.

A contractor’s expenses for time and materials work was reported on a form titled, Daily Report – Labor, Material & Equipment Form. This form was commonly referred to as “T&M” or “time and materials” slips.

Contractors were required to report on each T&M slip the hours worked by each tradesperson and the classification of that tradesperson. The classification of each tradesperson determined the rate of pay for that tradesperson and, therefore, determined the amount of money that the contractors were paid for that tradesperson’s time. For example, an apprentice tradesperson is billed at a lower hourly rate than a journeyman.

Contractors certified the accuracy of the information contained within the T&M slip. B/PB’s Resident Engineer’s Office was required to verify that the information contained within the T&M slip was substantively correct, but on occasions failed to adequately review T&M packets.

Claims for payment for time and materials work were submitted by the contractors to the project’s Claims and Changes Department for review. Part of B/PB's contractual obligations after October 1, 2001 included providing qualified personnel to staff the project's Claims and Changes Department. These personnel worked under the management, supervision, and direction of MTA. The Claims and Changes Department was responsible for reviewing contractors' claims for payment for T&M expenses and approving the claims for payment.

Contractors submitted thousands of T&M slips to the Claims and Changes Department in support of claims for payment due to claimed changes in the contract. Contractors also submitted spread sheets, summarizing the information contained on the T&M slips in support of the T&M packet.

Contractors at times recorded apprentice workers as journeymen workers on T&M slips, thereby inflating the cost of the work performed on the T&M slips. They also at times submitted summary spreadsheets that failed to record accurately the number of apprentices as having worked on T&M contract modifications, when in fact apprentices had performed some of the work.

A review of the certified payroll submitted by the contractors, to which the Claims and Changes Department or B/PB could request access, would have uncovered the false information.

As a result, certain contractors received some inflated payments that they were not entitled to receive. Three employees of one Central Artery/Tunnel contractor have pleaded guilty to federal criminal charges for falsely categorizing apprentice workers as journeymen.

Concrete Program

Approximately 321,000 truckloads of concrete were delivered to the project from 1998 through 2004. Per its contract, B/PB implemented a concrete testing program, which was reviewed and approved by MTA, MHD, and FHWA. The concrete quality assurance (QA) program on the Central Artery/Tunnel met the applicable standards required for highway construction. All concrete QA personnel were trained and certified to American Concrete Institute standards. MHD conducted regular independent assessments of the testing program and verified compliance of personnel and equipment with the Materials Program.

Concrete was supplied from multiple concrete suppliers and batch plants. MHD approved all concrete batch plants, and all plants were certified by the National Ready Mix Concrete Association. The project required each plant to have a computerized batching system so that all ingredients were automatically controlled and documented on the batch tickets. These tickets were checked randomly at the batch plants, and all tickets were reviewed at the point of delivery.

In July 2007, Aggregate Industries, the major concrete supplier, entered into an agreement with the United States and the Commonwealth of Massachusetts, pleading guilty in connection with a fraudulent scheme to deliver adulterated concrete. Out of approximately 192,900 truckloads of concrete, Aggregate Industries delivered 5,700 truckloads of non-specification concrete to the Central Artery/Tunnel. This concrete included recycled concrete that was more than 90 minutes old, concrete that had been adulterated with the addition of excess water, and concrete that was not batched pursuant to Central Artery/Tunnel specifications.

Aggregate Industries concealed this fraud by falsifying concrete batch slips delivered to Central Artery/Tunnel inspectors and/or representatives of the general contractors at the various construction sites. B/PB field engineers allowed "out-of-spec" concrete delivered by Aggregate Industries to be placed and failed to determine that all concrete delivered to the project met project specifications and was placed pursuant to project procedures.

The agreement required Aggregate Industries to pay $50 million to the federal and state governments and provide up to $75 million in insurance coverage for potential future structural maintenance costs related to its conduct.

Programmatic Upgrades

As part of the settlement agreement, both Bechtel Infrastructure Corporation (BINFRA) and Parsons Brinckerhoff (PB) will take specific actions to enhance their existing training, compliance, and quality assurance programs in order to improve long-term performance and ensure that future work benefits from lessons learned during the Central Artery/Tunnel project.

As part of the settlement agreement, both Bechtel Infrastructure Corporation (BINFRA) and Parsons Brinckerhoff (PB) will take specific actions to enhance their existing training, compliance, and quality assurance programs in order to improve long-term performance and ensure that future work benefits from lessons learned during the Central Artery/Tunnel project.

For BINFRA, these actions include:

  • adopting a quality management system certified to ISO 9001:2000 for all work for FHWA and/or the Commonwealth of Massachusetts;
  • prohibiting the use of adhesive anchors in overhead applications where public safety might be at risk, pending revision of current industry standards;
  • adopting and implementing design and construction specifications for slurry walls, and waterproofing and leak mitigation in tunnels and underground structures; and
  • making mandatory for all BINFRA field engineers an update of its existing course, “Ethics for Engineers,” and a new course, “Quality Management for Engineers.”

For PB, these actions include:

  • maintaining its ISO 9001 quality management system certification;
  • prohibiting the use of adhesive anchors in overhead applications where public safety might be at risk, pending revision of current industry standards;
  • adopting and implementing design and construction specifications for slurry walls, and waterproofing and leak mitigation in tunnels and underground structures; and
  • enhancing and expanding PB’s current ethics training, quality assurance training and technical certification programs.

ISO 9001 Certification

ISO is the world largest standards-development organization. Between 1947 and the present day, ISO has published more than 16,500 International Standards, ranging from standards for activities such as agriculture and construction, through mechanical engineering, to medical devices and the newest information technology developments.

ISO Standard 9001 establishes standards for an organization’s quality management system. The requirements cover every aspect of production, from top management commitment and customer focus to resources, employee competence, process management, quality planning, monitoring and measurement of processes, as well as processes to resolve customer complaints, corrective/preventive actions, and continual improvement of the quality management system.

In practice, the application of ISO 9001 may be driven by industry practices and customer preferences. Virtually all of Bechtel's work in the oil and gas industry, for instance, as well as in the conventional power sector is ISO 9001-certified. On the other hand, the nuclear industry operates to somewhat different and even more stringent quality standards, leaving ISO 9001 requirements moot.

BINFRA will convert its quality policy from “compliant with” to “certified to” the requirements of ISO 9001. Compliance with the standard requires an organization to perform an internal audit to verify that its processes conform to the standard. Certification requires an independent external body to audit the organization’s management system and verify that the system conforms to the requirements specified in the standard. BINFRA will use Lloyd's of London for this purpose; PB uses Underwriters Laboratory.


Cost Growth

The Central Artery/Tunnel is the largest and most complex urban transportation project ever undertaken in the United States. The initial cost estimate of $2.6 billion (in 1982 dollars) dated back to 1985, before B/PB was hired, and was based on a preliminary concept developed by state officials before detailed technical studies had been undertaken.

When the last roadway was opened in early 2006, the final cost forecast for the Central Artery/Tunnel was $14.6 billion—$12 billion more than advertised a quarter century earlier. Cost growth over 25 years of planning, design, construction, and commissioning was driven chiefly by the impact of inflation and immense increases in the size and complexity of the project over the original conception.

The single biggest contributor to rising costs was inflation. Following federal rules, the original cost estimate included no allowance or calculation for inflation. The cost of the project also rose due to extraordinary steps taken by state officials to accommodate the business community, neighborhoods, and other agencies and interest groups. This process made the design more responsive to community needs and secured public acceptance, but the resulting mitigation measures also made the project much more complex, time-consuming, and expensive. In all, according to state officials, the project undertook more than 1,500 separate mitigation agreements, accounting for a significant share of the Central Artery/Tunnel project’s total costs.

The major key cost drivers (shown in current dollars) include:

  • Inflation ($6.4 billion)
  • Major growth in project scope and traffic maintenance ($2.7 billion)
  • Environmental compliance and mitigation ($3 billion)
  • Accelerating the construction schedule ($600 million)
  • Accounting adjustments reflecting changes in government guidelines for allocating costs ($1.2 billion)

The most authoritative history of the project, a study by Harvard University scholars Alan Altschuler and David Luberoff, put the Central Artery/Tunnel’s cost growth in this context, “Public projects are now subject to a multitude of environmental, citizen participation, and other regulations, and are far more vulnerable to legal challenges. As one consequence many fewer large public works projects go forward; but as another those which do are far more expensive—since their budgets include larger, often vastly larger, amounts for mitigation and compensation.”1

Integrated Project Organization (IPO)

The Central Artery/Tunnel management structure evolved over the life of the project in response to the changing state government administrations, roles of the affected public agencies, and resource issues.

The initial project organization provided for parallel staffing at the senior level of both the Massachusetts Department of Public Works (later the MHD and MTA) and the B/PB team. For example, the MDPW's Project Director, Director of Design, and Director of Construction respectively managed the B/PB Program Manager, Design Manager, and Construction Manager, under the oversight of the FHWA Project Administrator.

On July 1, 1997, the MHD and the MTA entered into the Central Artery/Ted Williams Tunnel Project Management Agreement, effectively assigning MHD project management responsibilities to MTA. In the fall of 1997, MTA began considering the creation of an IPO to streamline the review and decision-making processes on the project and increase management efficiency and productivity.

MTA's implementation of the IPO resulted in changes in B/PB’s responsibilities and in the overall management of the Central Artery/Tunnel. The structure of the IPO was phased in through the implementation of a series of contract amendments, management directives, and issuance of project management plan revisions.

The first phase of implementing the IPO consisted of MTA taking over direct responsibility for several of the functional departments in the project management team. From January 1998 to June 1998, the following services, previously provided and managed by B/PB, were transferred to MTA:

  • Risk management
  • Environmental services management
  • Invoice services and archeology services
  • Communications and public affairs
  • External audits and administrative services
  • Procurement services

MTA managed the departments providing the services. Any B/PB employees needed in the department were seconded to MTA and began working under the direct supervision and control of MTA.

On July 1, 1998, MTA began the second phase of the IPO, the merging of the respective MTA and B/PB staffs to manage those services that had not been transferred to MTA. MTA and B/PB personnel were deployed throughout the management organization, with the best candidate available selected for each position. The IPO replaced the parallel structure of counterpart managers with a single project management team working within one organizational structure.
MTA sought final approval of the FHWA to implement the management changes by November 2, 1998. FHWA gave a conditional approval, pending the assurance that potential conflicts of interest were properly addressed. With the MTA assurance that appropriate safeguards were in place, the full implementation of the IPO commenced on November 16, 1998.

Although adopted with FHWA approval for the stated purpose of streamlining the management structure and trimming costs, the IPO also had the effect of blurring accountability and responsibilities. One of the best descriptions of the functional effect of the creation of the IPO is the National Academy of Engineers report, which states:

“…during the transition to the IPO structure in 1997-1999, the best-qualified person available for a particular managerial position was selected regardless of organizational affiliation (the position of project director, who reports to the chairman of the MTA was reserved for an MTA employee). In effect, B/PB is no longer in the role of a project Management Consultant but supplies highly qualified people to augment the staff of the MTA.”

For a more extensive examination of the history of the Central Artery/Tunnel, including the impact of the IPO, see "Lessons of Boston’s Big Dig" from the August 2007 issue of the Manhattan City Journal.

Tunnel Leaks

All tunnels built below the water table have some seeps and leaks. In addition to these small leaks and seeps, tens of thousands of gallons of storm water enter the tunnels on roadway surfaces when it rains or snows, much of it carried in by cars and trucks. Operational issues can add to this volume. For example, in 2007, water flows were further inflated when a 6-inch valve in the groundwater equilibration system was left in its fully open position, allowing groundwater to enter the tunnels. Such infiltration poses no hazard. Tunnel drainage system pumps handle these volumes with ease.

Managing and minimizing water intrusion is a normal and essential part of avoiding future corrosion of the structure and equipment. The initial strategy against leaks is to waterproof portions of the tunnel floors, walls, roofs, and joints during construction. No waterproofing system is perfect, however. Chasing water that inevitably seeps through walls and joints is not a repair—it is an integral and anticipated part of the construction. It is also an iterative process. It takes persistence to block off the multiple paths that water under pressure always finds or creates. On the Central Artery/Tunnel, crews are systematically locating and sealing spots where water enters in each of the various sections of the tunnels or underground utilities. The process is normally paid for by the contractors responsible for each of those respective sections.

Residual seepage in the tunnels will be addressed through a normal and ongoing maintenance program. According to the FHWA's tunnel maintenance manual, typical finished tunnels can assume a continuing trickle about equal to the output of one ordinary garden hose for each linear mile of tunnel. Over time, that small flow can add up to a number big enough to generate headlines: more than 2 million gallons per year per mile of tunnel, or about 12 million gallons annually for a tunnel as long as the I-93. In fact, the Central Artery/Tunnel’s tunnels bettered this norm for the past three years, even before construction was complete. For more information on water intrusion through 2005, please see Water Intrustion in the I-93 Tunnel.

The timetable for sealing the remaining small leaks slipped in 2006 when MTA diverted resources to other project needs. But Central Artery/Tunnel Project Manager Mike Lewis reported to MTA’s board in August 2007 that the ongoing leaks program has proven “effective” and that it would continue into spring 2008. About 500 small seeps in the roof girder bays remain to be sealed. A smaller number of leaks in utility conduits and other sources will also be sealed.

On December 17, 2007, the firm of Wiss, Janney, Elstner Associates, Inc. presented its report on Central Artery/Tunnel water infiltration to MTA. This report was part of Phase II of a stem-to-stern safety review of the Central Artery/Tunnel commissioned by then-Governor Romney following the July 10, 2006 ceiling panel collapse.

Wiss Janney found that the current leak rate of the Central Artery/Tunnel is well below the generally accepted norm. Wiss Janney noted that 670 known active tunnel leaks due to cracks, construction joints, and conduit or pipe penetrations are being addressed by the Central Artery/Tunnel project, which estimates that all known leaks will be remediated by mid-2008.

Wiss Janney noted that it is the nature of underground tunnels to experience some degree of leakage, regardless of efforts to avoid it. Operators deal with leaks on a case-by-case basis to eliminate or slow down leaks to a manageable level and “in this respect, the Central Artery/Tunnel is no different than other tunnels.” Wiss Janney recommended that MTA embark on a water management program to diligently control tunnel leakage to within industry norms and take appropriate measures to protect vulnerable structural and electrical systems.

Assuming a proper level of inspection and maintenance, including continued attention to metal coatings, the tunnels should provide excellent service into the next century.

David Luberoff and Alan Altschuler, Mega-Project: A Political History of Boston’s Multibillion Dollar Artery/Tunnel Project (Cambridge, MA: John F. Kennedy School of Government, Harvard University, Rev. ed., April 1996)., VI-6 to VI-8.